Fuel combustion and gas turbine engine combustors encounters many design problems when attempting to achieve optimum engine operation. High temperatures create material strength and longevity problems and also create thermal expansion problems. Smokeless combustion must be achieved with high efficiency. The flame must be easily ignited and stable against flameout at fuel lean conditions.
In an annular combustor, an annular dome supports the plurality of fuel nozzles in a circumferentially spaced manner. A cooled heat shield is interposed between the dome and the combustion chamber. Continuous annular shields have given way to segmented shields in modern high temperature combustors because of expansion and buckling of the continuous shields. With the segmented shields, one segment is secured to each fuel nozzle with the segments substantially abutting one another when hot. The segments, however, have a gap between adjacent segments when operating at lower temperatures.
When operating at the lower loading with fuel lean mixtures the cooling air passing between the spaced shields creates a curtain effect between adjacent nozzle flames. This limits the ability of adjacent flames to support the ignition of their neighbors and accordingly leads to poor ignitability and a tendency for early flameout.